Air curtains



A. BOYSEN AIR CURTAINS Aug. 21, 1962 2 Sheets-Sheet 1 Filed Nov. 3, 1959 VIE. l.

ITIL-12.

INVENTOR:

ARNE BOYSEN ATTYS' 17.4. iik# Aug- 21, 1962 A. BOYSEN 3,049,984

AIR CURTAINS Filed NOV 3, 1959 2 Sheets-Sheet 2 FIE1- FIE- El- INVENToR: ARNE BOYSEN BY www ATTYS 3,049,984 AIR CURTAINS Arne Boysen, Lidingo, Sweden, assignor to Aktiebolaget Svenska Flktfabriken, Stockholm, Sweden Filed Nov. s, 1959, ser. No. 850,557 3 Claims. (Cl. 98-36) In order to prevent an air exchange between two spaces having different air conditions and which for the passage of people and material are to communicate with another, it is known to use shielding means in form of an air curtain. A presumption for the intended effect of such an air curtain is that the air current is able to cross said passage uninterruptedly. It ha-s, however, been found that occurring changes with respect to wind and temperature produce a deilection of said air current resulting in a chance of greater or smaller -air exchange.

The present invention relates to a method to secure the shielding effect of an air curtain between two spaces at occurring variations in pressure difference between said spaces, and is characterized in that the introduced air forming said air curtain is regulated in such a way that said curtain is deflected from its normal position towards that space where a relative pressure increase occurs and that at the same time the air quantity-while maintaining the ow velocity constant-is caused to increase in direct proportion to the extent of deviation of said air curtain from its normal position.

The invention further relates to a device for the performance of said method, consisting of an air supply duct, provided with one or more distributing slots having a length corresponding to the intended extension of said curtain. Said device is characterized in that each of said slots is bounded by two rotatably journalled, inter-connected guiding vanes having -two alternately functioning turning centers and being so shaped that the free slot between said guiding vanes always will increase in the same ratio as the guiding vanes are turned to give the air curtain an oblique ilow direction. The device may suitably be provided with maneuvering means for an automatic adjustment of the guiding vanes, said means being inuenced by the air pressures on different sides of the air curtain. According to a suitable embodiment of the invention the device may have means for maintaining the pressure in the air supply duct at a const-ant value.

The invention will now be described more in detail with reference to the accompanying drawing showing an air supply duct provided with regulating means in accordance with the invention, wherein FIG. `l is a cross section of a passageway embodying an air curtain in accordance with the present invention;

FIG. 2 is an enlarged fragmentary cross section of an air supply duct having regulating means in accordance with the present invention;

FIG. 3 is a sectional view taken on the line 3 3 of FIG. 2;

FIG. 4 is a sectional view taken on the line 4 4 of FIG. 3;

FIG. 5 is a longitudinal sectional view taken intermediate a pair of guiding vanes; and

FIGS. 6, 7, and 8 are diagrammatic views of the guiding vanes as shown in FIG. 2, showing the operation thereof.

In the drawing two spaces 1 and 2 have different air conditions and a shielding air curtain 3 is to be maintained therebetween. An air supply duct 4 is arranged at one side of the free passage between the spaces y1 and 2, which air supply duct is provided with openings 5-51. In each opening two rotatably journalled guiding vanes 6 and 7 are arranged in accordance with the inven- States Patent O tion, between which vanes there is a vfree distributing slot 8. Sealing means 9 resiliently press against said guiding vanes along the whole length of same. According to the invention the guiding vanes 6 and 7 are journalled and shaped in such a way that-when being turned to either side, for instance to the positions shown in broken lines in FIG. 2 at 61 and 71 respectively giving the air curtain an oblique direction-the width of said free slot 8 between the guiding vanes simultaneously will be increased. In the illustrated embodiment this effect will be obtained by the fact that guiding vanes 6 and 7 and the adjacent iixed structure are provided with two alternately functioning the stub shafts 6b and 7b being located at the turning centers of the arcuate portions of vanes 6 and 7. In order to obtain such a turning of, for instance, the guiding vanes 6, the stub shafts 6b located at opposite ends of the vane are 4arranged to slide in a groove 11 being disposed in fastening means 10, arranged in the air supply duct at the both ends of the guiding vane. A groove 6c is arranged in the guiding vane 6 for a stub shaft 6a iixed to the fastening means, which shaft slides in said groove when the vane is turned to the right. 13 designates a spring, one end of which is fastened to said shaft and the other end of which is fastened to the guiding vane 6 (see FIG. 4). The purpose of said spring is to prevent the stub shaft from sliding in the groove 6c when the guiding vane is turned to the left. In the same way the guiding vane 7 is provided with similar elements, which in the drawing are designated 7b, `12, 10, 7c and 14. 15 tand 16 designate two sprocket wheels arranged at the ends of the guiding vanes, which sprockets are actuated by a rack gear 17. This gear is by means of a rod 18 connected to a control means 19 which at occurring changes of the pressures sensed by devices 20 `and 211 will displace said rod in one or the other direction and thereat will adjust the guiding vanes for obtaining a `changed ilow direction for the air curtain in accordance with the invention. Means of any desired type may be provided for maintaining the pressure in the duct 4 at a constant value. Such means are well known in the art but for illustrative purposes there is shown a flo-w control device 22 which is capable of sensing the pressure of air entering the duct 4 and acting to control the effect of the air supply means (not shown).

In the operation of the guiding vanes, as shown in FIGS. 6 to 8 inclusive, the air ow passage between the vanes increases when the vanes are deflected from their normal position in which the air curtain is directed vertically downward. As shown in FIG. 7, in the normal position of the vanes, there is a clearance designated W1 between the vanes. Deflection of the air curtain to the left, for example by displacement of the rack 17 to the right (see FIG. 2), causes the vane 6 to pivot on the stud 6a, the stud 6b moving in the slot 11. The vane 7, on the other hand, pivots on its stud 7b, the slot 7c moving over the pivot stud 7a so that the vanes 6 and 7 assume the position 6" and 7" as shown. In this position, the clearance between the vanes is increased as indicated at W2 which, because of the maintenance of the air pressure differential equal, causes an increase in the quantity of flow through the clearance. By the same token, when the 'air curtain is deflected to the right, as shown in FIG. 8, the vane 6 is pivoted to the position 6 on the stud 6b, and vane 7 is pivoted to the position 7 on the stud 7a, thus increasing the clearance space as indicated at W2. Thus, when the vanes deflect the air curtain to the right or to the left, the clearance space between the vanes, and therefore the quantity of air flow, increases in proportion to the extent of the deflection of the air curtain.

As shown in FIGS. 3, 4 and 5, the sprockets or gears for one of the vanes are shown as being located on the ends of the vanes. They may be secured to the ends of the vanes in any of the many Ways in which artisans employ for securing parts together. For example, if the body of the vane 6 is made of wood, wood screws may be employed for securing the gears to the vane; if the vane is made of sheet metal (as is very common in this art) the gears may he secured by sheet metal screws or by bolts; if the vane is made of solid metal (and it need not be, for it may as well be made light), the gears may be secured to the vane body by machine screws. In any case it is possible to use glue, solder, welding, or other appropriate means as are now so commonly employed.

The stub shafts 6b, as stated above are provided on the ends of the vane and at the center of the gears and of the arcuate portions of the vane. The stub shafts are rigidly secured either directly to the vane or to the gears, depending on which may he more convenient. FIG. 4 shows this arrangement very clearly and it is equally apparent in FIG. 3. Now, in operation, when the stub shafts 6b move along in the arcuate -grooves 11 of the fixed members 10 adjacent the ends of the vane, the vane will move bodily to some extent along the length of the rack but the relationship of lthe gears is such that an operational relationship between the teeth of the rack `1"! and the teeth of the gears 15 will be maintained in a satisfactory manner. In this bodily movement of the vane the resilient portion of the duct which carries the sealing means 9, being light, will bend enough to permit the necessary movement to take place.

'I'he pins 6a and la are secured to the iixed portions 10 adjacent the ends of the vanes 6 and 7 respectively and these pins ope-rate in arcuate grooves 6c and 7c in the ends of the gears and vanes as shown in FIGS. 3, 4, and 5 and as clearly indicated in dotted litres in FIG, 2.

Now when the vanes are turned about their center stub shafts 6b or 7b respectively, Aand when the vane is turned in the direction where the center stub shaft maintains a iixed position at the end of a slot (11 or 12) the gear and vane will turn to move the slots 6c, 7c along the fixed stub shafts 6a or 7a as may be required.

Without departing `from the scope of the invention, the shape and support of the guiding vanes as wel-l as the adjusting means may be varied in a number of ways.

What I claim is:

l. A method of securing improved shielding effect of an air curtain moving in a path between two spaces at different pressures upon variations in the pressure difference between said spaces comprising the steps of introducing air at constant pressure in the form of an air curtain transversely between said spaces, deecting said curtain from its normal path toward that space wherein the relative pressure increases, and maintaining the flow velocity in said air curtain constant while increasing the quantity of fiow in direct proportion to the extent of deflection of said air curtain from its normal position.

2. Apparatus for securing an improved air shielding eiect of an air curtain moving in a path transversely of the length of a passageway between two spaces at different pressures upon variations in the pressure difference between said spaces, comprising in combination, an air supply duct having an air supply opening of a length corresponding to the width of said passageway, said opening being located above the passageway, a pair of air guiding vanes mounted in said opening in spaced-apart relationship, said vanes being of the same length as said opening, means sealing said vanes with the sides of the opening, leaving the space between the vanes open for the passage of air to form an air curtain transversely of said passageway, each of said vanes having a vane-carried stub shaft secured to each vane at each end, a gear on each vane concentric with the vane-carried shaft, a iixed anchorage support in the opening at each end of the vanes, an arcuate slot in the iixed supports for each vanecarried stub sha-ft, an anchorage-carried stub shaft secured to said fixed anchorage support and spaced transversely at a distance from each vane-carried stub shaft, said vanes having an arcuate slot for each anchoragecarried stub shaft, a rack engaging the gears of both vanes to turn them together, and resilient means urging said vanes to turn in opposite directions about their vanecarried stub shafts, the arrangement causing the vanes of the pair to turn on alternate stub shaft centers as the vane gears are turned by the rack for increasing the air space between the vanes in proportion to the turning of said vanes from a normal intermediate position.

3. Apparatus yas set forth in claim 2, which further includes means for operating said vanes in accordance with the pressure differential of the two spaces.

References Cited in the file of this patent UNITED STATES PATENTS 983,877 Cumming Feb. 14, 1911 2,082,335 Hart lune 1, 1937 2,149,976 McKnight Mar. 7, 1939 2,863,373 Steiner Dec. 9, 1958 2,935,925 DOoge May l0, 1960 

